Transportation of chemicals



Oct. 19, 1943. R. B. MacMULLlN TRANSPORTATION-0F CHEMICALS Filed Sept. 20, 1939 3 Sheets-Sheet 1 INVENTOR oct. 19,1943. n. B. MaCMULLlN 2,332,242

y TRANSPORTATION 0F CHEMICAL: i

ATTORNEY oct. 19, 1943. R, B, MM'MULLIN f 2,332,242

TRANSPORTATION OF CHEMICALS Filed Sept. 20, 1939 3 Sheets-Sheet 5 Patented Oct. 19, 1943 UNITED y f STATES PATENT OFI-ICE Robert 'Burns MacMullin, Niagara Falls, N. Y., assignor to The Mathieson Alkali Works, Inc., New' York, N. Y., a corporation of Virginia Application September 20, 1939, Serial'No. 295,716 Claims. (Cl. 23-293) My invention relates to improvements in thel transportation of caustic soda.

The caustic soda of commerce is ordinarily brought to a concentration of at least 50% NaOH at the point of production prior to shipment-to the point of use. The transportation of lower concentrations would of course involve the handling of more water than caustic. The three concentrations generally'available in commerce are 48%-52% NaOH, 65%-'70% NaOH and 98%- 100% NaOH. l

The 50% NaOH caustic soda is an aqueous solution having a freezing point o f about -50 F. At ordinary atmospheric temperatures caustic soda of this concentration has but slight corrosive action with respect to ordinary steel and it therefore can be' shipped and handledin containers of ordinary steel for many purposes. For some pur-f` pgses, however, nickel or nickel lined'containers or containers protected with a film of an appropriate coating composition resistant to such corrosion must be used to prevent contamination with iron. But in any eventa'weight of water equal to the weight of NaOH must betransported `when caustic soda is shipped as, 50%` NaOH 4 doubling the cost of transportation per unit of NaOH. y

The 70% caustic soda has a melting -pointb'fy about 147 F. and .is customarily charged into the shipping container as liquid at a temperature above its melting point, During shipment the caustic soda cools and may partially or even completely solidify unless inconvenient and expensive steps are taken to keep it at a temperature ab'ove the melting point, either-by supplying heat or by insulation. To the extent thatl solidication occurs, itis necessary tore'melt the 70% NaOH caustic soda in order to eiect its discharge from the container upon delivery. The shipment and handling of caustic soda at 70% NaOH concentration has the advantage .that 7 parts by weight of NaOH are transported for every 3 parts of water, but 70% NaOH caustic sodaat temperatures above itsmelting point isquite corrosive with respect to iron and steel'and, to a somewhat point thus involving a corrosion problem'of extreme dimculty.

Anhydrous caustic soda is usually shipped and handled either in solid masses or asa aked 0r lgranulated product. The fused anhydrous caustic soda may be run into steel containers in which it is allowed to solidify or it may be aked or granulated and then packed for shipment and handling in hermetically sealed steel containers. The shipment and handling of caustic soda as the anhydrous product eliminates the useless transportation of water, but concentrations exceeding about 80%85% NaOH cannot be attained in the ordinary vacuum evaporators 4so that the nal concentration is-conventionally eiected in directly-tired fusion pots and this fusion as ordinarily practiced involves such contamination of the product with metallic impurities 'that a supplemental, and expensive,-nish ing operation is required to eliminate impurities introduced into the caustic soda during the concentration. The containers in which anhydrous caustic soda is shipped and handled, moreover, y represent an added element of cost since they must ordinarily be discarded as of no Ifurther use upon delivery of the product.

The bulk of the caustic soda of \commerce is ultimately. used in concentrations substantially lower than 50% NaOI-I. For example, in the rayon industry, one of the larger users of caustic soda, the caustic soda is commonly used at a concentration of about 18% NaOH. Special requirements of the users of the caustic soda must be satisfied. example, extreme purity with respect to iron and' nickel and other heavy metals) is required. Subject to suchlimitations, the-'use'vwishes to have the causticlsoda delivered atthe point of use for the lowest p ssible cost per unit of NaOH and the cost of transportation is an important component of the iinal cost to the user, Other components of this nal cost are the cost of pro-- duction, the cost of concentration and the cost of any required nishing.

My invention provides improvements in the` transportation of caustic soda which assist in I reducing the nal cost of this product to the user 'l e tions such that the product was solid at ordinary atmospheric temperatures in railway tank cars. I have found that a satisfactory load of naked In the rayon industry again, for a not anticipated. When water was run into a tank of caustic .soda through the conventional ports provided on top of the tank, initial solution was rapidly followed by stratcation of the water and of the liquor forming as the caustic soda dissolved which so reduced the average rate of solution that long and indefinite periods were required to bring the contents of the tank to a condition such that they could be conveniently discharged as a liquid. Also, the heat of solution of the caustic soda tended to involve local rises in temperature which in turn involved contamination with the metal of the tank or tank lining or destruction of protective coating compositions. I have now discovered however that, if water is added to the lower part of Asuch a container thus charged with solid caustic soda containing about 65%85% NaOH, the caustic soda dissolves very rapidly and without stratifi- .cation or local overheating to form a solution conveniently and easily discharged from the container. -Towfacilitate the rapid formation of a uniform solution of the caustic soda I may blow the contents of the container with air for a vshortA period after the introduction of therequisite water. It is possible in this manner to discharge a railway tank car thus charged with free flowingv particles, naked or granulated, of caustic. soda containing about 65%85% NaOH in a mattei` of minutes. Liquid solutions of suiiicient concentration forfmost if not all industrial purposes can thus be formed and the concentration of the .solution can be kept below that at which any special difliculties with respect to corrosion are involved. Further, the formation of this solution appears to proceed with sufficient regularity and uniformity to avoid local overconcentrations as well as local overheating ywithin the container in which the solution occurs so thatdimculties with respect to corrosion are avoided here as well as in subsequent handling of the caustic soda solution. l

In practicing my invention, after concentrating the caustic .soda at the point of production to about 65-85% NaOH, I reduce the product to granular or naked form, I then charge the transportation container with these free flowing parlticles, and, after delivery of the transportation container, I discharge thecontainer by introducing water into the lower part of the container,

I full of the granulated or flaked product is usually suillcient to receive this volume of water, but I` may introduce the total volume of water in two or three steps, discharging the liquid solution formed after each successive introduction, particularly to form final solutions of lower concentrations. f The required concentration, of the ca'usticsoda'is economically attained and is attained without any-such contamination of the product as might require special finishing operai tions. The charging of the transportation container with the naked or granulated product is simple and expedient. Eiliciency with respect to transportation cost is promoted because of the concentration of the product. For many purposes the usual steel containers can be used, and where special protection with respect to metallic contamination is required the ordinary nickel or nickel lined containers or containers protected with the ordinary corrosion resistant coating compositions can be used notwithstanding the concentration prevailing during the actual transportation of the caustic soda. And the discharge of the caustic soda from the container upon delivery in the form of solution of concentration appropriate, for industrial application is simple and expedient anddoes not require that the transportation equipment be tied up for an unusual time.

To illustrate the industrial application of my invention, I have included a chart in the accompanying drawings which, using 70 F. as a representative initial temperature, graphically indicates (A) the final temperatures attained, and thus the temperature rise, when Water sufficient to produce asolution of volume equaling the apparent volume of the solid caustic soda. is added in accordance with my invention, (B) the nal concentration of the liquid solutions of caustic sodaI thus produced, (C) and the apparent density of the solid caustic soda prior to the addition of water. 'I'his chart constitutes Fig. l of the accompanying drawings. 'Ihe other figures of the accompanying drawings illustrate two forms of railway tank car together with the appropriate equipment for charging and discharging the tank car with caustic soda in accordance with my invention. In the accompanying drawings, Fig. 2 represents a tank car and loading bin in elevation, Fig. 3 represents the same tank cai` and loading bin in plan and Fig. 4 represents the same tank car and loading bin in end elevation,

Fig. 5 represents an end elevation of Aa modiiied form of tankl car together with a loading bin and Fig. 6 represents aplan of the tank car and loading bin illustrated in Fig. 5.

Referring to Figs. 2, 3 and 2i of the drawings, the tank car 1 illustrated is'the conventional railway tankV car except for the provision of a plurality of charging ports 8 anda grid of distributing pipes 9 arranged in the lower part of the car tank and connected through a manifold to an external connection IIJ.F The car tank is provided 'with the usual bottom discharge connection Il. A bin l2 with appropriate. connections I3 is disposed to permit charging of -the car tank through the several charging ports 8 simultaneously.' Conventional apparatus I4 for flaking or granulating the causticsoda may be positioned immediately above this bin l2 in association with appropriate conveying mechanism I5 for distributing the naked or granulated'caustic soda through the bin l2. The several pipes 9 are each provided on their lower side with spaced aper tures to distribute the fluids introduced through connection lllJover the lower part of the car tank. The same parts are designated by the same reference characters in Figs. 5 and as in Figs. 2, 3 and 4. The car tank insteadof being essentially circular in crosssection, however, is extended vertically, as illustrated in Fig. 5. With a car tank of this configuration, increased car loads can be accommodated within established railway in two or more steps.

standards notwithstanding the reduced apparent density of the ilaked or granulated caustic soda.

In carrying out my invention in the equipment such as that illustrated in Figs. 2 to 6 inclusive, thecar tank is charged, at the point of production, with solid caustic soda' in the form of free flowing particles' containing about 65%-85% NaOH through the connections I3 and the ports 8. The car tank is then sealed and the car put in transit.` Upon delivery water is run into the car ytank through connection I and the distributor pipes '9 in the required volume. For example, the car tank may be substantially lled with the naked or granulated product and then substantially filled with added water. Or the tank car,

somewhat less than full of the flaked or granulated product, may be substantially filled with added water. Or the charged tank car may be filled and drained and again iilled and'drained The solid caustic soda dissolves rapidly in theintroduced water, but -withvout'am,1 substantial local overheating or local vailing temperature. This minimum amount is readily determined by reference to the solubility .of caustic soda in water and the concentration of the caustic soda with which the container is charged. Within the range of concentration approximating 65%-85% NaOH, a volume of water suiiicient to form=a solution in volume approximating the apparent volume of the flakcd or granulated solid caustic soda will produce' a solution. liquid @at ordinary atmospheric temperatures. Somewhat smaller quantities of water can and the distributor y be used to produce more' concentrated solutions,

within the minimum limit above indicated, but suiiicient Water should be added in ani7 case to avoid concentrations so high as to involve objectionable corrosion of the particular equipment used for shipping and handling the solid caustic soda and the delivered caustic soda solution.

For example, the amount of introduced water may be regulated to produce a liquid solution ofcaustic soda of NaOH concentration. l In this manner my invention can be made available, for example, to former users of 50% NaOH caustic soda solutions without involving any change in the handling 'of the delivered caustic soda. Working with a prevailing temperature of 70 F., it will be apparent by reference to Fig. 1 of the accompanying drawings that with a aked solid caustic temperature, F., used for purposes of illustration in Fig. 1. v

The quantities of water required to form a 50% NaOH solution from a flaked or granulated product of concentrations NaOH in accordance with my invention is indicated in the following tabulation. This tabulation also indicates the order of temperature change involved in formation of the solution'. It will be noted that the maximum 'temperature rise is butv100 F. Opposite the per cent NaOH concentration of the flaked or granulated product in the first column, the quantity of water in -parts by weight to be added per 100 parts of the naked or granulated product to form a solution of 50% NaOH concentration appears in the second column and the temperature change (approximate) appears in the third column:

1 n i 1n Per cent Parts F.

The quantities of water required to form solutions of other concentrations are readily determined by conventional calculations. Temperature rises are higher for solutions of lower concentration, when r'nade from the same strength of ilake.

In summary, my invention providesimprovements in the transportation of caustic soda which combine several important economic advantages. My invention reduces the cost of transportation by reducing the proportion of water inevitably transported with caustic soda shipped at a concentration of 50% NaOH forvexample. 'At the same time, it avoids the disadvantages of shipment of caustic soda in higher concentrations.

as hitherto practiced. The concentration of caustic soda required in carrying out my invention, concentrationsapproximating 65%-85% NaOH, are economically attained inconventional apapparatus, and without complications with respect to contamination. Caustic soda of 65%- NaOH concentration is economically reduced to granular or flaked form in conventional apparatus. easily handled in transportationcontainers can be constructed of conventional materials, and, when required, conventional linings or protective coatings can be used. Protection of the container with respect to high temperatures or high NaOH concentrations isnot necessary for many purposes and for most purposes involves no unusual difficulty. The unloading of the containers upon v, delivery is f simple and requires but little time. The solution soda ranging from 65% to 85% NaOH and ranging from about 51 to about 57 pounds per cubic foot in apparent densitythe introduction of water in volume forming a solution approximately equalling in volume the apparent volume of the solid caustic soda produces a liquid solution of caustic soda ranging from somewhat less than y 40% to somewhat more than 50% NaOH concentration. It will be .obvious that the flaked kor granulated caustic soda-in the container and the introduced water need not be -at the same temperature, and that the practice of my invention does not depend upon the existence of the most producers of caustic soda have found it necessary to reduce the product to the anhydrous form for storage when storage at the point of proof the solid caustic soda in the container for delivery does not involve the hazards of local overheating or local overconcentration and does not incur suiilcient temperature rise to involve any unusual difliculties with respect to contamina'- tion. l

My'invention will also permit the producer of caustic soda to store it, economically, in the form of a aked or granulated product of 70%-80% NaOH concentration, for example. Hitherto,

duction became necessary for any reason.

ranging from 65% to 85% This granulated or flaked product is` connection with loading. The

I claim:

1. In the transportation of caustic soda, the improvement which comprises substantially lling a tank car with solid caustic soda in the form of relatively cool free-owing particles containing about 65%-85% NaOH, and discharging the tank car by rst introducing relatively cool water into the bottom thereof in an amount sumcient to form an aqueous NaOH solution liquid at ordi-A nary atmospheric temperature but insulcient to cause a temperature rise of more than about 100 F. and insufcient to cause the temperature.

to rise to a value substantially exceedingv 147 F., and thereafter without further dilution running oi the resultant liquid solution of the caustic soda from the tank car. k

2. In the transportation of'caustic soda, the

improvement which comprises substantially lling a tank car 'with caustic soda in the form of relatively cool free-owing particles containing' 65%-85% NaOH, and discharging the tank car by rst introducing relativelycool water into the soda originally charged in the form of free iiowing particles, said caustic soda having a temperatur'e not substantially exceeding '70 F. and containing not less than about 65% nor more than about 80% NaOH, comprising rst introducing water into the bottom of the container in an amount suiiicient to form an aqueous NaOH solution liquid at ordinary atmospheric temperature but insumcent to cause thev temperature to rise to a value-substantially exceeding 145 F., and thereafter/ without further dilution running oii' the resultant liquid solution of the caustic sodaI from the container.

4. In the transportation of caustic soda, the improvement which comprises substantially filling a tank car with solid caustic soda in the form of relatively cool free-flowing particles containing about 65%-85% NaOH and discharging the tank car by introducing relatively cool water into the bottom thereof in an amount suilicient to form an aqueous solution containing less than approximately NaOH but insuilicient to cause a temperature rise of more than about 100 F. and insufficient to cause a ilnal temperature substantially exceeding 147 F., blowing the contents of the tank car with air,` and thereafter without further dilution running 0E the resultant liquid solution of caustic soda `from the tank car.

5. In the transportation of caustic soda, the improvement which comprises introducing linto, a large transportation container a substantial body of caustic in the form of free-flowing particles containing not less than about nor substantialy more than about 80% NaOH, said caustic having a temperature not substantially exceeding about F., and discharging the caustic by first introducing Water at a temperature not substantially exceeding 70 F. into the bottom of the transportation container in an amount suilcient to provide a liquid solution containing less than approximately 50% NaOH but not less than about 40% NaOH, and thereafter without further dilution running oi the resultant liquid solution of the caustic soda from the transportation container. I

ROBERT BURNS MACM'ULIJN. 

